Liquid displacement pumps



June 23, 1970 1 R. 11.1. SKINNER 3,516,758

LIQUID DISPLACEMENT PUMPS' Filed June 4. 1968 v 2 Sheets-Sheet 1 BY, WATTORNEYS June 23, 1970 R. T. J. SKINNER LIQUID DISPLACEMENT PUMPS 2Sheets-Sheet Filed June 4, 1968 vgwrorz BY ATTORNEYS United StatesPatent 3,516,758 LIQUID DISPLACEMENT PUMPS Robert Thomas John Skinner,Kenilworth, England, assignor to Joseph Lucas (Industries) Limited,Birmingham, England Continuation-impart of application Ser. No. 557,043,June 13, 1966. This application June 4, 1968, Ser. No. 734,441 Theportion of the term of the patent subsequent to Dec. 24, 1985, has beendisclaimed Int. Cl. F04d 15/00, 27/100 U.S. Cl. 415-126 4 ClaimsABSTRACT OF THE DISCLOSURE A liquid displacement pump in which a body isprovided with an interior cavity, a bladed rotor cavity, an inlet and anoutlet disposed at respective angularly spaced positions in the cavity,and the side wall of the cavity defines a part annular recess adjacentto the rotor edge, and extending between the inlet and the outlet.Control means is actuable to vary the effective combined volume of thecavity and the recess which is available for the flow of liquid betweenthe inlet and the outlet.

BACKGROUND OF THE INVENTION This application is a continuation-in-partof my application No. 557,043, filed June 13, 1966, now abandoned, andentitled: Liquid Displacement Pumps.

In my earlier application I have disclosed a liquid displacement pump ofthe type having a body, a bladed rotor mounted within a cavity in thebody, an inlet and and outlet in the body communicating with the cavityand a part annular recess in the side wall of the cavity in the bodyadjacent to the rotor periphery, with the recess extending around therotor intermediate the position of the inlet and that of the outlet.

The present application relates to a liquid displacement pump of thistype generally as disclosed in my earlier application and in additiondiscloses parts and features of the pump not referred to in the originalapplication.

The object of the invention is to provide a pump of the kind specified,in a convenient form.

SUMMARY OF THE INVENTION In accordance with the present invention, aliquid displacement pump of the type specified is characterized by theprovision of control means whereby the effective combined volume of thecavity and recess in the body which is available for the flow of liquidbetween the inlet and the outlet, can be varied.

The invention will now be described by way of example with reference tothe accompanying drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of apump incorporating the present invention,

FIG. 2 is an end elevation view, and

FIG. 3 is a fragmentary cross-sectional view on the line III--III inFIG. 2.

DETAILED DESCRIPTION OF THE INVENTION These drawings illustrate a pumpwhich incorporates altenative arrangements as will be described, and itis to be understood that certain parts can, if desired, be omitted. Thepump is suitable for supplying liquid fuel to a gas turbine engine. Thepump has a multi-part body which defines a generally cylindricalinternal cavity 11 within which is mounted a bladed rotor 12 connectedto a shaft 13 which can be driven by the engine to which the pump isintended to supply fuel. The rotor blades, in this example, extendradially and are flat on both faces except at the outer end of theleading face of each blade. At this position, the blade is formed with aconcave recess indicated at 12a of part cylindrical cross-section, toform a scoop at the outer end of the blade. The axial depth of the rotoris equal tothe width of the recess so that, except for the center, thewhole of the cavity is swept by the rotor blades. In the cylindricalwall of the cavity are a pair of diametrically opposite tangentialoutlets 14a communicating with respective outlet passages 14- asillustrated in FIG. 2.

One sidewall of the cavity 11 is defined by an inlet plate 15 having apair of diametrically opposite inlet openings 15a which communicate witha central inlet port 16 formed in the body 10. These inlet openings 15ain the plate 15 are disposed near the inner edges of the rotor bladesand are angularly spaced from the outlets 14:: respectively.

The opposite sidewall of the cavity 11 has an annular recess 17 ofrectangular channel shape in cross-section. The outer peripheral edge ofthis coincides with the cylindrical wall of the cavity 11 and the radialwidth of the recess is approximately a quarter of the radius of therotor 12. The recess 17 is divided by a pair of fixed abutments 23secured in the body to form a pair of semicircular recess portions.Radially aligned with one end of the recesses is one of the inletopenings 15a and radially aligned with the other end of each is one ofthe outlets 14a.

The base wall of the recess 17 is constituted by the crown of an annularpiston 18 mounted in the body 10, with this piston being movable in adirection parallel to the axis of the rotor toward and away from therotor under control of springs 24 acting beneath the abutments 23. Atthe opposite end of the piston 18 is defined a space to which fluidunder pressure can be admitted to control the position of the piston 18against the action of its springs 24. These springs 24 urge the pistonaway from the rotor 12 so that when no fluid pressure exists in thespace at the end of the piston, the recess 17 will be of maximum depth.

In use, as the rotor 12 rotates, flow of liquid takes place through theinlet openings 15a, between the rotor blades and into the respectiveportions of the recess 17, and thence again through the spaces betweenthe rotor blades to the outlets 14a. As the liquid flows through thespaces between the blades and through the recess 17 it tends to follow agenerally part-toroidal path about a center coincident with the rotoraxis between the inlet openings and the outlets respectively; themagnitude of this toroidal movement and therefore the pressure and rateof flow of the liquid leaving the outlets are dependent upon thephysical dimensions of the respective recess portions. By varying theposition of the annular piston 18, the volume of the recess 17 availablefor liquid flow can be increased or decreased and it is known that thesmaller the recess, the less will be the increase in pressure generatedby the toroidal flow. When the recess 17 is completely filled by thepiston 18, there will be no tendency for toroidal flow to be generatedand the pump will operate in the manner of a normal centrifugal pump.

The pump thus far described can be used as such, but alternatively oradditionally to the arrangements for controlling the pressure in theoutlet, the position of the inlet plate 15 may be varied. For thispurpose, the inlet plate 15 has a flange and is urged toward the rotor12 by a spring 19. The outer periphery of the inlet plate 15 is steppedand engages in a stepped bore in the body 10.

Between the respective shoulders of the body and inlet plate is definedan annular space 25, with which communicates a fluid pressure inletpassage 26, shown in FIG. 3.

Admission of fluid under pressure to the space causes the inlet plate 15to be moved against the action of the spring 19. This moves the inletopenings 15a away from the rotor so that the volume of the cavityavailable for flow is increased. The flow of fluid liquid will now takeplace, not from two specific points around the rotor, but towards theoutlets 14a before entering the spaces between the blades. The pump willoperate more like a conventional centrifugal pump, having no recess 17,than when the inlet plate 15 is adjacent to the rotor side face. Thepressure rise across the pump will under these circumstances, be lessthan when the inlet plate 15 is closely adjacent to the rotor. To guidethe inlet plate 15 and limit the permitted travel towards and away fromthe rotor, the flange of the plate 15 has a plurality of elongated slots20 engaged by a pair of screws 21, 22.

The inlet plate 15 is angularly adjustable to move the inlet openings15a towards and away from the outlets 14a respectively, thus varying theeffective lengths of the recesses which are available for flow betweenthe inlet openings and the outlets respectively. Releasing of the screws21, 22 engaging in the slots 20 in the inlet plate enables the angularadjustment of the inlet plate 15 to be effected.

If the movable inlet plate is employed instead of the movable piston 18,the body 10 will be provided with a fixed recess 17.

In an alternative construction, there is one recess with one abutmentonly and the inlet opening is at one side of it and the outlet at theother. The double arrangement described and illustrated affords a betterdistribution of loads on the piston thus reducing the risk of thisjammmg.

In a still further form the outlets are formed in a ring defining theouter peripheral wall of the cavity. This ring is angularly movable tovary the distance between the inlet openings and outlets. Adjustmentsmay be achieved in the manner adopted for angular adjustment of theinlet plate 15 in the form illustrated.

It is to be understood that in the form illustrated two forms of volumevariation are provided. In practice only one would be provided in apump.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

1. A liquid displacement pump comprising a body defining an interiorcylindrical cavity, a bladed rotor rotatably mounted in the cavity inthe body, said body having an inlet and an outlet disposed at respectivepositions, spaced angularly about the rotor rotational axis, the outletbeing disposed in the cylindrical wall of the cavity, a part annularrecess being provided in one side wall of the cavity, the recess havingan outer peripheral edge adjacent to the cylindrical wall of the cavity,said recess extending around the rotor intermediate the position of theinlet and that of the outlet, and control means actuable to vary theeffective combined volume of the cavity and the recess which isavailable for flow of liquid between the inlet and the outlet.

2. A liquid displacement pump comprising a body defining an interiorcylindrical cavity, a bladed rotor rotatably mounted in the cavity inthe body, an inlet and an outlet in the body disposed at respectivepositions, spaced angularly about the rotor rotational axis, the outletbeing disposed in the cylindrical wall of the cavity, a part annularrecess in one side wall of the cavity, the recess having an outerperipheral edge adjacent to the cylindrical wall of the cavity, saidrecess extending around the rotor intermediate the position of the inletand that of the outlet, and control means comprising a piston formingthe base of the recess in the body, and means for moving said piston ina direction parallel to the rotor rotational axis to vary the volume ofsaid recess which is available for flow of liquid between the inlet andthe outlet.

3. The liquid displacement pump as claimed in claim 2 in which there aretwo inlets and two outlets in the body and the recess is divided intotwo portions extending between the respective inlets and outlets.

4. A liquid displacement pump comprising a body defining an interiorcylindrical cavity, a bladed rotor mounted for rotation in the cavity,said body having an inlet and an outlet disposed'at respective positionsspaced angularly about the rotational axis of the rotor, said outletbeing disposed in the cylindrical wall of the cavity, one side wall ofthe cavity having an annular recess of rectangular channel shape incross section, the outer peripheral edge of the recess coinciding withthe cylindrical wall of the cavity, a pair of fixed abutments secured inthe body and dividing the recess into a pair of semi-circular portions,the inlet being radially aligned with one end of the recess and theoutlet with the other end, and control means for varying the volume ofthe recess which is available for liquid flow between the inlet and theoutlet, said control means including an annular piston having a crownmounted in the body, with the crown defining the base wall of therecess, spring means beneath the abutments for moving the piston in adirection parallel to the axis of the rotor, a space at the opposite endof the piston into which pressure fluid can be introduced to control thepiston position against the action of the spring means, and said springmeans normally urging the piston away from the rotor when no fluidpressure exists in the space.

References Cited UNITED STATES PATENTS 1,768,313 6 /1930 Ferguson et al10396 X 2,765,745 10/1956 Sadler et a1. 10342 2,957,424 10/ 1960Brundage et a1. 10397 3,417,705 12/1968 Skinner 103-97 LEONARD H. GERIN,Primary Examiner US. Cl. X.R.

